Arming device for mines



June 1957 E. R. HABERLAND 2,795,189,

ARMING DEVICE FOR MINES Filed Jul 12, 1955 INVENTOR E. R. HABERLAND BY /MiA/i;

, 2,795,189 Patented June 11, 1957 ARMING DEVICE FOR MINES Ernest R. Haberland, Silver Spring, Md., assignor to the United States of America as represented by the Secretary of the Navy Application July 12, 1955, Serial No. 521,652 8 Claims. (Cl. 102-16) (Granted under Title 35, U. S. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates to arming devices for underwater ordnance such as mines and more particularly to a device wherein osmotic pressure is utilized for the force necessary to produce the mechanical movement required in the arming procedure.

The present method of producing mechanical movement in arming a naval mine involves the use of hydrostatic pressure to force a plunger from a normal rest or safe position to a new or armed position. This arrangement creates certain arming problems especially in the case of shallow water mines where the depth of the mine in the water is not great enough to make available adequate hydrostatic pressure to perform the normal arming functions. Obvious expedients, such as increasing the piston area, are defeated by the presence of varying internal mine pressure. This varying internal pressure is a result of temperature variation and barometric pressure at the time the mine is sealed. For example, a mine sealed at a relatively high atmospheric pressure and immersed in cold sea water would have a drop in internal pressure. Conversely, a positive internal pressure would be created in a mine sealed at 40 F. and immersed in sea water 75 F. In the latter situation a mine would require deeper water than the normally desired arming depth in order to accomplish the arming function. Thus the change of.

internal pressure has the effect of arming the mine in either deeper or more shallow water than desired.

Two methods of overcoming this difi'iculty have been devised. One method is to use a vacuum reference and the other a compensating spring which is calibrated in temperature and set when the mine is at its final assembly point. The vacuum reference system is expensive to build and the compensating spring is subject to the human error of not being set at assembly.

In general the present invention utilizes the phenomenon of osmosis to create the force necessary to efiect suflicient mechanical movement for arming the mine. It is a well known principle of physical chemistry that when a solvent and a solution are separated by a semipermeable membrane the solution will diffuse through the membrane to attempt to equalize the concentration of solution molecules on both sides of the separating membrane. Osmosis may take place not only between a pure solvent and a solution but also between two solutions of difiering concentrations, the flow of the solvent being from the solution of low solute concentration to that of high solute concentration. Obviously, as molecules pass through the membrane to the high solute concentration there is a corresponding increase in volume on the latter side of the membrane. If the high solute concentration is prevented from increasing in volume by a confining chamber a resulting pressure is created. The pressure within this chamber 2 which is just sufiicient to prevent osmosis is known as the osmotic pressure of the solution.

In employing this principle of osmosis the present invention presents a pressure chamber in which there is confined a concentrated sugar solution which is in direct contact with a snap-over spring disc. The concentrated solution is separated from the outside of the body, or more precisely when the mine is immersed in sea water the solu-' tion is separated from the sea water, by an appropriate semipermeable membrane. As sea water contacts the membrane the low solute concentration of the sea water in contrast to the sugar solution causes the water molecules to pass through the membrane into the sugar solution thereby creating osmotic pressure within the pressure chamber.

to arm the mine.

An object of the present invention is the provision of a mine arming pressure device wherein the immersion of a mine in sea water will cause sufficient osmotic pressure to provide arming action.

Another object is to provide a mine arming mechanism in which the arming function is completely independent of mine water depth.

A further object of the invention is the provision of a mine arming mechanism which is independent of internal mine pressures caused by temperature and humidity variations.

Still another object is to provide an arming device which is simple and inexpensive in construction and fabrication.

Still other objects and advantages will be apparent from the following description taken in connection with the accompanying drawings, in which:

Fig. 1 is a longitudinal sectional view of one form of the arming device showing the device in the initial or unarmed position;

Fig. 2 is a longitudinal view partly in section showing the device in the armed position; and

Fig. 3 is a fragmentary sectional view showing a modification of the switch means used in the invention.

Referring now to the drawing, wherein like reference characters designate like or corresponding parts throughout the several views, there is shown in Fig. 1 the pressure device generally designated as 10 which comprises a body member 11 made of brass, stainless steel or the like. Within the body member are a plurality of axially aligned bores or cavities. One cavity forms the pressure chamber 12 which is filled with a concentrated sugar solution 13. This solution is confined at the lower end of the chamber by a dish-shaped spring 14 which in the initial, or unarmed position as shown in Fig. 1 presents a convex surface in contact with the sugar solution 13. Spring 14 has an annular flange 15 held against boss '16 by means of an annular clamp nut 17. Clamp nut 17 has a stepped construction consisting of a threaded boss 18 and an annular abutment shoulder 19. The clamp nut is screwed into the lower end of body member 11 in engagement with a threaded bore 20. As shown in Fig. 1 the clamp nut 17 has an axial passage 21 permitting direct fluid or mechanical communication between spring 14 and the remainder of the arming mechanism (not shown) of the mine.

An annular shoulder 22 is formed between the pressure chamber 12 and bore 20. Formed in the surface of this shoulder is an annular recess 23 adapted to receive a conventional O-ring type seal 24. This seal prevents escape of solution 13 from the pressure chamber into the interior of the mine. As clearly shown on the drawing the diameter of annular flange 15 of the spring member is less than the diameter of internal bore 20. This feature permits slight radial movement of the spring flange since, if the outer perimeter of the flange was confined, the force required to cause spring member 14 to snap over At a predetermined pressure the spring disc will react to actuate the mechanical movement necessary from its convex to a concave position would be excessive.

smaller bore 27 which in turn connects with the pressure chamber 12 by means of a still smaller axial bore 28.

As will be seen in Fig. 1 the annular shoulder 29 formed between bore 25 and bore 27 provides a seat for a membrane member 30. Any one of a number of semipermeable artificial membranes may be used to separate the concentrated sugar solution 13 from the sea water. Unwaterproofed cellophane is a successful and convenient substance from which the membrane may be formed. Examples of other membranes are parchment, collodion prepared from pyroxyline, ethyl ether and ethanol. Copper ferrocyanide and nickel ferrocyanide precipitated within the pores of clay vessels is also a successful semipermeable membrane. When a membrane of cellophane, parchment or collodion is used it must be sandwiched between adequate porous supports. In the preferred embodiment of the invention membrane 30 is backed with powder metallurgy plates 31 and 32. These plates may be composed of any material suitable for the purpose such, for example, as unglazed porcelain making the backup plates porous to liquids and at the same time possessing rather high strength This inherent strength permits the porous plates to withstand the normal hydrostatic pressure from the sea Water and the internal high osmotic pressure thereby preventing the rupturing of the membrane 30. Plate 31 has a fiat cylindrical shape which is coincident with the configuration of bore 27. Plate 31 fits within bore 27 and rests against annular shoulder 33 formed between bore 27 and bore 28. Plate 32 fits within a circular recess 34 in the annular frame member 35 which serves not only to house the porous plate 32 but also to retain the membrane in contact with shoulder 29 and O-ring 36 which is located in an annular recess 37 formed in the shoulder 29.

As will be seen in Fig. l the membrane, the porous back-up plates and the frame member are all retained in place by means of an annular lock nut 38 externally threaded to permits its connection with the threaded outer portion 26- of the bore 25. Lock nut 38 has a central axial opening 39 extending therethrough in alignment with the axial opening 40 in frame member 35. Openings 39 and 40 provide the passageway for sea water to reach membrane 30 by way of the porous back-up plate 32 once the mine is immersed.

Since the pressure amplifying device described herein is designed to be inserted into the body of a mine, the preferred form of housing 11 is provided with an externally threaded portion 41 best shown in Fig.2. The device can thus be threaded into a cavity within the mine body with the under surface. 42 of annular flange 43 forming a contact surface with the mine body. This contact surface may conveniently house an O-ring seal ,44

(Fig. l) or other convenient means for preventing access of sea water to the interior of the mine. 7

In Fig. 1 there is shown one embodiment of aswitch means which can be utilized to react to the snap-over motion of the spring 14. to arm the mine. A conventional microswitch 45 is secured to the inner face of a cover plate 46 which in turn is removably attached to clamp nut 17. A spring biased contact finger 47 extends from the switch casing in the direction of the snapover'spring 14-. By properly locating finger 47 with respect to the spring, it will be seen that snap action of the spring will depress the finger causing an electrical contact to be made thus arming the mine.

, On Fig. 3 is shown another embodiment of the switch means. In this embodiment a pressure type switch generally designated as 48 is secured to the cover plate 46a. A portion of the switch is exposed to the passage 21a by means of an opening 49 in the cover plate. With this type of arrangement the snap action of the spring will transmit pressure through an appropriate fluid in passage 21a whereby an electrical contact will be made within the pressure switch 48. An O-r-ing is preferably provided at 50 to insure a pressure tight seal between plate 46a and clamp nut 17.

In the use of this pressure device it will be seen from the drawings that once the mine is immersed in sea water, the Water is given immediate access to the semipermeable membrane 30. Since the sugar solution 13 which is disposed within pressure chamber 12 is of high solute concentration as compared to the sea water the water molecules will diffuse through the membrane from outside to inside in an attempt to equalize these concentrations. Since an increase in volume of solution 13 is restrained due to its confinement in chamber 12 by spring 14 a pressure is created in the chamber sufficient to flex the dishshaped spring 14. This pressure is known as osmotic pressure. The dish-shaped or Belleville snap-over spring 14 is made with an appropriate radius of curvature and thickness to require a predetermined value of pressure to enable the spring to reverse its position from that shown in Fig. l to that shown in Fig. 2. Accordingly,

when the osmotic pressure within the chamber 12 reaches or exceeds this predetermined value the spring will suddenly snap over from a convex to a concave position. As previously set forth, the motion of the spring provides the necessary movement to actuate the selected switching 1 means and thus perform the arming function of the mine.

" The time required for the osmotic pressure to build up to a sufi'icientforce to invert the Belleville spring provides adelay arming feature of the mine.

'From the description of the invention it is apparent that a device has'been provided whereby the immersion of a mine in sea water will initiate the process of osmosis whereby sufiicient pressure will be developed within the device to carry out the arming function which has heretofore been dependent upon hydrostatic pressure of the sea water. The use of osmotic pressure obviates difficulties presented by temperature and barometric pressure variationsand renders the mine arming mechanism free from dependency upon depth of the mine below the surface of the water.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

-What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. An arming device for use in a naval mine comprising a body member having a chamber therein, a concentrated sugar solution in said chamber, passage means connecting said chamber with the exterior of said body member and mine, porous elements secured Within the body and extending transverse to said passage means, a semipermeable membrane arranged between said elements, and pressure responsive means secured within said body member and in contact with said solution. 7

2. The invention as set forth in claim 1 wherein said pressure responsive means includes a dish-shaped spring. 3. The invention as set forth in claim 1 in which said pressure responsive means comprises a movable diaphragm in contact with said solution and a switch means in proximity with said diaphragm whereby movement of the diaphragm will actuate said switch means.

' 4. The inventionas set forth in claim 3 in which said movable diaphragm consists of a metallic dish-shaped spring. i

S. A hydrostatic pressure amplifier for use in the arming of naval mines comprising a body member having a chamber therein, said chamber having two openings therein communicating with the exterior of said body member, a semipermeable membrane covering the first of said openings, a pair of supporting porous plates covering said first opening and disposed adjacent the opposite faces of said membrane, a flexible snap-over spring secured to said body member and covering the second of said openings, said spring having an initial position presenting a convex configuration toward said chamber and being adaptable to snap-over to a concave configuration upon application thereto of a predetermined pressure developed in said chamber, a concentrated sugar solution disposed in said chamber and adjacent said spring, said solution being adaptable to develop said predetermined pressure.

6. The invention as set forth in claim in which a switch means is fixed to said body member adjacent to the opposite side of said spring from said solution Whereby movement of said spring in response to the predetermined pressure will cause said spring to contact said switch means.

7. An arming device for use in a mine comprising a body member having a chamber therein, a concentrated solution in said chamber, passage means connecting said chamber with the interior of said body member, a semipermeable membrane secured within the body member and transverse to said passage means, a pair of porous back-up members transversely fixed Within said passage means for supporting said membrane therebetween, and pressure responsive means in contact with said concentrated solution.

8. An arming device for use in a naval mine comprising a body member having a chamber therein, a concentrated solution in said chamber, passage means connecting said chamber with the exterior of said body member and mine, a semipermeable membrane secured within the body member and transverse to said passage means, a pair of porous back-up members transversely fixed Within said passage means in a manner to support said membrane therebetween, a movable dish-shaped spring diaphragm forming a Wall portion of said chamber and having one face thereof in contact with said solution, and a switch means fixed in proximity with said diaphragm on the opposite side of said diaphragm from said solution whereby movement of said diaphragm will actuate said switch means.

References Cited in the file of this patent UNITED STATES PATENTS 1,520,086 Sanderson Dec. 23, 1924 1,719,959 Bast July 9, 1929 FOREIGN PATENTS 311,620 Ger-many Apr. 4, 1919 

